Effects of monopolar radiofrequency heating on intradiscal pressure in sheep

Background contextNo previous study has assessed the effect of monopolar radiofrequency (RF) heating on intradiscal pressure.PurposeTo determine the decrease in lumbar intradiscal pressure after monopolar RF heating.Study design/settingIntradiscal pressure was measured in sheep lumbar discs treated with monopolar RF heating.MethodsTwo monopolar RF heat treatments at 90°C were applied for 2 minutes each to lumbar intervertebral discs of sheep. Intradiscal pressure was measured in live sheep at 0, 7, 14, 21, and 28 days posttreatment. Pressure measurements were taken with a microtip pressure transducer. Electrodes were inserted but not activated in separate discs as a sham control. In vitro sheep spine of different age groups, loading conditions, and electrode orientations were similarly heat treated and intradiscal pressures were measured.ResultsIntradiscal pressure was significantly reduced 1 week after monopolar RF heating and remained stable through the 4-week observation period. The RF electrode orientation, the age, and the type of disc loading have significant effects on the amount of initial intradiscal pressure reduction.ConclusionsMonopolar RF heating can reduce intradiscal pressure in the lumbar spine of sheep.